Sitting outside the picturesque Barge Inn, near Alton Barnes, darkest Wiltshire, at a table by the canal, away from the chatter coming from other tables, one can just make out the sound of wheat fields rustling in the summer breeze. It's a siren call, dangerously alluring to the easily led: "Come flatten me", it says, "roll me, stroke my ears and swirl magic patterns through my hair... bend me, shape me anyway you want me..."

Old dogs, who know better, seek refuge in the tiny "croppies room" - set aside by the pub's owners to satisfy (and openly encourage) its current reputation as the unofficial centre for crop circles studies. Years ago the scene was played out in the tack room of the Waggon and Horses, Beckhampton, where the walls retain the ghosts and the bloodstains of unforgotten conflicts. Times have changed; besides, the Waggon lacks a web-site, and a camp-site, and it's not so close to Polly's farm.

A notable proportion of the most impressive formations have "miraculously" appeared on the land of their most vociferous proponent. Strange attraction? Apart from her duties as a farmer's wife, Polly Carson acts as resident dowser, seer of spaceships, and staunch defender of the faith. In the long hot summer of 1990 she witnessed the arrival of thousands of paying visitors to the first of the massive pictograms which have since appeared annually in the vast East field, about half a mile from here. This year's extravaganza - an unearthed stanza to an almost-forgotten poem - is arguably the most impressive of all, resembling a giant double-helix as it twists and binds for 200 metres or more. Some say the 12 large circles are chakra points, the smaller circles representing energy movement. The majority, including most of the experts, have it down as DNA - the stuff of life - with its eighty 'molecules' no doubt perfectly positioned, giving some of us a unique insight into the quanta.

According to the Daily Telegraph, the day after the formation arrived Polly faxed a sketch to the House of Commons (it wasn't mentioned specifically to whom), along with her rough outline for official funding: "It's time the government stopped fobbing everyone off with the excuse that these are made by hoaxers", she pleaded. Lucy Pringle, who resigned as vice-President of the ailing Centre for Crop Circles Studies earlier this summer, along with its Patron, Lord Haddington, and President, Archie Roy, remains equally determined. As one who was cured of a recurring shoulder injury while standing in a formation, she's naturally hopeful that the drastic cuts in Wiltshire's health budget are only the start of a positive shift in priorities. Lucy describes the recent arrival as "mind-blowing". Then, ignoring all the evidence to the contrary, she adds, "We are still no nearer the answer as to who or what is behind this phenomenon." Lucy is joined in the line of deserving causes by 'internationally renowned' dowser Richard Andrews, who claims to have spent £60,000 in his years as an amateur cerealogist. But his friend Busty Taylor perhaps spoke for everyone who has actively studied the phenomenon for long enough: "I'm broke and depressed", he muttered, but with more emphasis on the latter.

Around the bar, however, booze-loosened lips tell a different story. A huddle of crop-watchers plot the night's best vantage points. They invariably settle for Knap Hill car-park, providing the perfect overview of East field. Typically, after "who or what" has bolted. Catching hoaxers is their main priority nowadays (none have been caught to date, despite a large reward offered by the National Farmers Union), but some privately suggest that these self-styled 'hoax-busters' have been known to indulge in a spot of circum-cereal artistry of their own. "There were nine of us on the hill that night", says one, "and five had wet trousers, if you know what I mean." I assume he means from the knees down, for just as the true circlemakers remain elusive - sensibly slipping in to the fields long before closing-time - so too the extraterrestrial motherships, prototype orbiting microwave weapons, plasma vortices, Nephilim giants, Gaia's node-blowing, rutting elves, and whatever other unlikely causes are argued out of earshot.

Not that conventional wisdom has been totally abandoned. At the next table, Paul Vigay is eagerly showing off his custom-built black box, freshly tweaked. "When the light flashes", he tells his friends, "it means a circle's genuine." Accordingly, his device "went haywire" in the DNA formation. Others tell stories of circles-related camera failures, or miraculous healings, and how they may soon have a litmus-test to determine 'hoaxed' from 'real'. As night draws in, three men who've been suspiciously quiet all evening make to leave, one of them checking his pockets as he heads for the door. There's no string visible - not that anyone else would notice, or admit to noticing. As the door opens, the siren's call wafts in, stronger now as light falls.

The most commonly used argument against hoaxing is "Why bother?" Brian Eno writes in his diary, A Year with Swollen Appendices: "A way of doing something original is by trying something so painstaking that nobody else has ever bothered with it. (..) Then the question arises in the mind: Why are they going to all this trouble? I like this question. I like any question that makes you start thinking about the 'outside' of the experience - because it makes the experience bigger." Listening to that call, one senses that, by dawn, when bleary-eyed investigators set out to investigate, and the three men head for home (aching legs and sides, but satisfied), another devotional masterpiece will be etched into the Wiltshire landscape, as if by magic.